The present invention pertains generally to analog electronic timepieces which incorporate stepping motors to rotationally drive the timepiece hands, and more particularly to improvements in the manner of energizing the motor coil to obtain stable operation of the stepping motor.
Conventional analog electronic timepieces, such as watches, clocks and the like, employ stepping motors to rotationally drive the timepiece hands through suitable gearing. The stepping motors comprise a stator, rotor and drive coil, and circuitry incorporated in the timepiece generates and applies drive signals of alternate polarity to the drive coil to excite the coil and accordingly rotationally drive the rotor. Typically, the drive signals are in the form of drive pulses of alternate polarity, the drive pulses having sufficient pulse width and height to suitably excite the drive coil so as to impart the necessary drive torque to rotationally drive the rotor under normal load conditions.
These prior art constructions suffer the drawback that they require precise timing of the application of the drive pulses to the drive coil and improper timing results in mis-operation of the stepping motor. For example, if the drive pulses are cut off too soon, insufficient torque will be applied to the rotor to rotationally advance the rotor to its next rest position and the rotor will return back to its previous rest position thereby causing the stepping motor to miss rotations.